default file system, was: Comparison to Workstation Technical Specification

[Ian Malone]

On 28 February 2014 20:45, Adam Williamson <awilliam at redhat.com> wrote:
> On Thu, 2014-02-27 at 23:16 -0700, Chris Murphy wrote:
>> On Feb 27, 2014, at 11:07 PM, James Wilson Harshaw IV <jwharshaw at gmail.com> wrote:
>>
>> > I apologize, I guess I did not get the whole background out of it.
>> >
>> > What filesystems are we considering?
>>
>> It's XFS vs ext4 and Server WG has agreed on XFS on LVM.
>
> As a server WG member I voted +1 on XFS as I have no particular
> objection to XFS as a filesystem, but I do think it seems a bit
> sub-optimal for us to wind up with server and desktop having defaults
> that are very similar but slightly different, for no apparently great
> reason.
>
> ext4 and xfs are basically what I refer to as 'plain' filesystems (i.e.
> not all souped-up btrfs/zfs stuff), they're stable, mature, and
> generally good-enough for just about all cases. Is xfs really so much
> better for servers, and ext4 so much better for desktops, that it's
> worth the extra development/maintenance to allow Desktop to use ext4 and
> Server to use xfs?
>
> Basically, what I'm saying is that if Desktop would be OK with using
> xfs-on-LVM as default with all choices demoted to custom partitioning
> (no dropdown), as Server has currently agreed on, that'd be great. Or if
> we could otherwise achieve agreement on something.
>

As you say they are 'plain' filesystems. Though I now regret not
sending my small datapoint in before the Server WG decision. That's
that a while ago, after using XFS for a long time we started putting
new filesystems onto ext4 and in the past month we moved probably our
largest remaining dataset (1.1TB) from XFS to ext4, the main reason
has been flexibility with resizing. Particularly the XFS 32bit inode
ceiling, (inode64 not working well with NFS).
1TB doesn't sound very big. These are imaging datasets in a research
environment, files going from small text to images at tens of MB (some
bigger, but not the dominant type). Projects usually get their own FS
(for a variety of reasons including backup, audit and budgeting
reasons). And often it's not known how large a project will eventually
be, so filesystems get extended as appropriate. With XFS we have to
take care to avoid the 32bit inode ceiling, and most recently found a
filesystem that refused to take any more files for some other reason,
even after creating a new clean copy. We didn't get to the bottom of
that, and moved the data to ext4.
Which is not to say XFS is a bad decision, there's plenty of people
using it for other tasks, but I looked through the Server WG meeting
and couldn't see mention of the for/against arguments. If my ramble
above demonstrates anything it's not really about XFS, it's that
server admins have reasons for choosing an FS and the scope to look at
and change to alternatives. Default FS on the Server is not actually a
massive impact, LVM is a different decision and makes sense there.
LVM on a workstation though, well, you can make it the default, but a
couple of releases ago I started turning it off and will continue
doing so. It adds an extra level of complication to management which
doesn't gain you anything on a workstation.

-- 
imalone
http://ibmalone.blogspot.co.uk